The present invention relates to a cylinder-operable key switch comprising a cylinder housing and a cylinder plug mounted rotatably therein, which acts upon an electrical switching device.
Key switches of this type are increasingly fitted into electronic equipment in order to determine whether an individual is entitled to operate the equipment or to maintain control over the equipment. Because of the high electrostatic potential of a person relative to earth voltage flash-over from the cylinder lock to the fixed contacts of the switching device could occur during insertion of the key. The consequence is then, in general, a malfunctioning of the electronic equipment, since the fixed contacts, which are in general connected to integrated circuits, cannot take such high loads. Attempts have been made, in such a design, to provide the cylinder housing with an insulating plastic sheathing, and to locate the switch side in a cup-shaped control armature opened up towards the key side, which is itself covered by a cup-shaped housing cap which is also made of insulating material. The axially-orientated design which results, however has a relatively great construction depth as can be seen from DE. No. 83 15 464.